One type of prior art semiconductor device is a ball grid array (“BGA”) device 10, generally depicted in FIG. 1. A BGA device 10 typically includes a substrate 12 carrying electrical conductive paths 14 and 16 on opposed surfaces 18 and 20 thereof, and electrical paths 22 formed within through-holes 24 through the substrate 12. The surface 18 of the substrate 12 also carries a semiconductor chip 30 that includes thereon and therein a variety of transistors and other devices.
The transistors and other devices of the chip 30 are rendered electrically continuous with selected ones of the paths 14 by wires 32 which are bonded to external transistor-connected pads on the chip 30 and selected paths 14. Selected paths 14 are connected to selected paths 16 via the through-hole paths 22. Eutectic solder balls 34 on the paths 16 permit the ultimate connection of the chip 30 to terminals or pads of utilization circuitry. The chip 30, the wires 32 and other portions of the device 10 may be covered with or encapsulated in insulative material 36 of selected formulations.
During and after the production of the BGA device 10, it is subjected to various visual, electrical and other inspections and tests. Ultimately, the completed device 10 is delivered to a packaging station, generally depicted by the reference numeral 38 in FIGS. 1 and 2, where the device 10 is packaged for delivery to and use by a customer.
The bonding of the wires 32, the encapsulation with the insulative material 36 and other operations utilized to produce the device 10 are typically carried out so that when the completed device 10 arrives at the packaging station 38, a first or upper surface 40 of the device 10 is oriented upwardly, while a second or lower surface 42 of the device 10 is oriented downwardly. This positioning of the device 10 orients the balls 34 downwardly.
Typically, and referring now to FIG. 2, large numbers of devices 10 are continuously delivered to the packaging station 38 oriented with their balls 34 down. Selected quantities of the devices 10 are then conveniently placed into multiple pockets 48, one device 10 per pocket 48, formed in a tray 50, sometimes referred to as a waffle pack, with their balls 34 down. A cover 52 may then be placed over and removably secured to the waffle pack 50 to retain the devices 10 therein. The waffle pack 50 and the contained devices 10 are then shipped to a customer.
Customers object to receiving the devices 10 in the waffle packs 50 ball-side-down. One reason for this objection is that customers' utilization of the devices—typically removal from the waffle pack 50 and placement in and connection to other circuitry—requires that the devices 10 be ball-side-up. Absent intervention by the device manufacturer, a customer must invert each device 10 into a ball-side-up orientation after its removal from the waffle pack 50.
Prior manufacturer intervention in this area has taken the following form: After a quantity of devices 10 have been loaded into an uncovered waffle pack 50, a second inverted waffle pack 52 is placed and held thereover so that the pockets 48 in each waffle pack 50,52 are aligned. At this point, the waffle pack 50 is below the superjacent waffle pack 52. The waffle pack 50,52 “sandwich” is then inverted reversing the upper and lower positions of the waffle packs 50,52 so that the waffle pack 50 originally holding the devices is now upside-down. This inversion allows the devices 10 to fall from the pockets 48 of the waffle pack 50 ball-side-up into the pockets 48 of the now lowermost, right-side-up waffle pack 52. The waffle pack 52 is then covered and shipped to a customer, who is able, as desired, to remove the devices 10 therefrom ball-side-up.
Typically, waffle packs 50,52 for BGA devices 10 contain numerous pockets. Aligning these pockets in the waffle packs 50,52 can be difficult and time-consuming. It is likely that some of the devices 10 will not drop into the pockets 48 of the waffle pack 52 upon inversion of the packs 50,52 because of misalignment of the pockets 48,48 or because of a device 10 “cocking” in the pockets 48 of one or the other pack 50,52. It has also been found that the application of force to the packs 50,52 during the inversion—such as may occur when the packs 50,52 are tapped to encourage the devices 10 to fall or due to the impact of the devices 10 against the pockets 48 in the pack 52 incident to falling—may damage the devices 10.
One aim of the present invention is the provision of a method and apparatus which simplify orienting devices 10 according to customers' wishes, which method and apparatus obviate the shortcomings of the prior method.